|1. First entry.
Even if the foreskin is manually retracted during foreplay, the bunched-up prepuce prevents the rim of the glans from making unobstructed contact with the vagina on first entry. Sensation for both partners is diminished.
|2. Part-way through the first thrust stroke.
The foreskin may retract sufficiently for both partners to experience the sensation of the rim of the glans being in direct contact with the vaginal wall, but this is not a certainty.
|3. First deep penetration.
This is the nearest equivalent to circumcised intercourse; the glans probably will be fully exposed at this point unless the male has phimosis. In that event, it is probable that the initial entry will be made with the foreskin not retracted and the glans will remain at least partially covered throughout coitus.
|4. Part-way through first retraction stroke.
Friction between the vaginal wall and the shaft skin of the uncircumcised penis tends to drag the foreskin over the glans.
It is at this point that the body fluids of the female become trapped against the male’s mucosal inner foreskin, with implications regarding female-to-male STI transfer if infection is present.
|5. Completion of first retraction stroke.
Unless the foreskin becomes hooked behind the coronal rim of the glans (possible in males with mild paraphimosis), the glans becomes covered at this juncture. Subsequent thrust strokes are likely to leave the male “masturbating inside his own foreskin”. This does not impart great sensations to the female, but ejaculation will still occur. As long as the tip of the glans is exposed at ejaculation fertility is not diminshed, but the sexual experience is degraded.